Preheat oven to 350°.Grease and flour two 9x5 loaf dishes.Whisk flour, sugars, soda, salt and baking powder in large bowl.In a separate large bowl, mash bananas.Add sour cream, butter, vanilla, and eggs to the bananas. Whisk until well blended.Gently fold the bananas into the flour just until all flour has been incorporated.Pour into prepared dishes and bake for about one hour.Check after an hour with a toothpick and if still gooey then add 5 minutes, checking each time to see if the bread is done.When ready, the loaves will be a dark, golden brown.